February 23, 2012 — Researchers from the US Centers for Disease Control and Prevention (CDC) are calling for all states to further restrict or prohibit the sale or distribution of products made from unpasteurized ("raw") milk in the wake of data showing that risk for disease is 150-fold higher after consumption of nonpasteurized dairy products, and that 60% of the resulting outbreaks involve children. CDC epidemiologist Adam J. Langer, DVM, MPH, and colleagues reported their analysis of disease outbreaks from nonpasteurized dairy products in an article published in the March issue of Emerging Infectious Diseases.
Although the distribution of nonpasteurized dairy products in interstate commerce has been prohibited by the US Food and Drug Administration (FDA) since 1987, sale of unpasteurized products within the state where they are produced is regulated by each state. During the time of the study (1993 - 2006), sale of nonpasteurized milk was legal in 25 states.
During that period, the CDC researchers found 121 outbreaks of dairy-related diseases for which the product's pasteurization status was known. This included 73 (60%) outbreaks involving nonpasteurized products, although such products account for less than 1% of total dairy product consumption. In outbreaks involving milk, 82% were from nonpasteurized milk. In outbreaks involving cheese, 42% were from cheese made from unpasteurized milk.
Outbreaks involving nonpasteurized dairy products resulted in 1571 illnesses, with a median of 11 patients, a hospitalization rate of 13%, and 2 deaths. All of the outbreaks from nonpasteurized dairy products were caused by bacteria, most commonly Campylobacter spp (54%), Salmonella spp (13%), and Shiga toxin–producing Escherichia coli (4%), which have animal reservoirs.
Outbreaks involving pasteurized dairy products (which account for 99% of approximately 2.7 trillion pounds of milk consumed during the study period) included 2842 illnesses, resulted in a hospitalization rate of 1%, and caused 1 death. The most common causative agents were norovirus (44%) Salmonellaspp. (20%), and Campylobacter spp (13%). Norovirus has a human reservoir.
"These results suggest that outbreaks caused by nonpasteurized dairy products are probably caused by pathogens in the dairy environment, which would be eliminated by proper pasteurization, and that outbreaks caused by pasteurized dairy products are probably caused by contamination of the products at some point after pasteurization," the authors write.
Of the outbreaks associated with unpasteurized dairy products, 75% occurred in 21 states where it was legal to sell raw milk products during the study period.
"This study shows an association between state laws and the number of outbreaks and illnesses from raw milk products," said Robert Tauxe, MD, MPH, deputy director of the CDC's Division of Foodborne, Waterborne and Environmental Diseases (DFWED). "Restricting the sale of raw milk products is likely to reduce the number of outbreaks and can help keep people healthier. The states that allow sale of raw milk will probably continue to see outbreaks in the future," Dr. Tauxe told Medscape Medical News.
Outbreaks from unpasteurized milk also disproportionately affect people younger than 20 years (60% vs 23% from pasteurized milk). The authors write, "Public health and regulatory authorities are obligated to protect persons who cannot make fully informed decisions (e.g., children) from potential health hazards. Dietary decisions for younger children, in particular, are often made by caregivers. The American Academy of Pediatrics advises against giving nonpasteurized dairy products to children and recommends that pediatricians counsel caregivers against use of these products."
"While some people think that raw milk has more health benefits than pasteurized milk, this study shows that raw milk has great risks, especially for children, who experience more severe illnesses if they get sick," said study coauthor Barbara Mahon, MD, MPH, deputy chief of CDC's DFWED Enteric Diseases Epidemiology Branch. "Parents who have lived through the experience of watching their child fight for their life after drinking raw milk now say that it's just not worth the risk," she told Medscape Medical News.
Of the known sources for 9 of the 15 outbreaks that occurred in states where sale of nonpasteurized dairy products was illegal, 7 (78%) were associated with products obtained directly from the dairy farm, 1 was limited to members of a family who consumed nonpasteurized milk from their own cow, and 1 was associated with products obtained under a "cow shares" communal program, which the CDC report describes as "a scheme used to circumvent state restrictions on commercial sales of nonpasteurized dairy products." Cow share owners argue that they have the legal right to drink raw milk from the cow they partly own.
The CDC researchers also note, "[I]n recent years, foodborne outbreaks involving nonpasteurized dairy products have been reported in association with traditional nonpasteurized products marketed to the growing Hispanic community in the United States."
The researchers warn, "Consumption of nonpasteurized dairy products cannot be considered safe under any circumstances."
In a related development, on February 22 a federal court granted the FDA a permanent injunction preventing Amish farmer Daniel L. Allgyer and his Rainbow Acres Farm from distributing packaged raw milk and raw milk products across state lines from his Pennsylvania farm to participants in a cow share program in the Washington, DC, metropolitan region.
Emerg Infect Dis. 2012;18:385-391.